CN111373296B - Optical aperture expansion arrangement for near-eye displays - Google Patents

Abstract

An optical aperture expansion arrangement particularly useful for near-eye displays employs a waveguide (30, 140, 145) having a wedge-like configuration (25, 26) to generate and couple out two modes of image illumination propagating along the waveguide. Various embodiments employ a rectangular waveguide in which image illumination propagates by quadruple internal reflection. In some cases, a wedge-like configuration is combined with an array of partially reflective interior surfaces (45, 150) to achieve two-dimensional aperture expansion.

Description

Optical aperture expansion arrangement for near-eye displays

technical field

The present invention relates to near-eye displays, and in particular, the present invention relates to optical aperture expansion arrangements for near-eye displays.

Background technique

Some near-eye displays are based on waveguides used to expand the aperture of a small projector to a larger aperture to display to the viewer's eyes. The waveguide includes an outcoupling mechanism to deliver light from the waveguide to the eye.

Aperture expansion is usually subdivided into two stages, with sequential expansion along two dimensions. The second dimension providing the output to the eye can be based on a waveguide containing internal facets commercially available from Lumus Ltd. (Israel), or a diffractive waveguide containing a diffractive surface for outcoupling the image can be employed. Optical components for waveguides.

Various arrangements can be used to provide aperture expansion in the first dimension. An example is described in PCT Patent Publication WO 2017/141242 (hereinafter "the '242 publication"), in which this is achieved by a wedge-like configuration at the end of the waveguide, which forms a parallelogram structure when viewed from the side. Coupling in and out.

Contents of the invention

The present invention is an optical device that provides aperture expansion that is particularly useful in near-eye displays.

According to the teachings of the embodiments of the present invention, an optical device is provided, comprising: a first optical waveguide having an elongated direction, the first optical waveguide having a first pair of parallel faces and a second pair of parallel faces, the first pair of The parallel faces and the second pair of parallel faces are parallel to the direction of elongation, forming a rectangular cross-section, for guiding light by quadruple internal reflection at the first pair of parallel faces and the second pair of parallel faces, each ray undergoing internal reflection is given by This defines a set of four conjugate propagation directions, at least a portion of the first optical waveguide is delimited by a first wedge-shaped shaping surface and a second wedge-shaped shaping surface, the first wedge-shaped shaping surface is configured such that it is aligned with the Light rays corresponding to at least a portion of the injected image propagating in a first direction of the first set of conjugate propagation directions are deflected to propagate in a second direction of the second set of conjugate propagation directions by reflection at the first wedge-shaped shaping surface, and The second direction forms a smaller angle with the direction of elongation than the first direction, and wherein the second wedge-shaped forming surface is parallel to the first wedge-shaped forming surface so as to align the direction along at least one of the second set of conjugate directions. The propagated image is deflected to propagate in at least one of the first set of conjugate directions, and the image propagated in one of the first set of conjugate directions is coupled out of the first optical waveguide.

According to another feature of an embodiment of the invention, the first wedge-shaped shaping surface is an outer surface of the first optical waveguide.

According to another feature of an embodiment of the invention, the first wedge-shaped forming surface is coated with a reflective coating.

According to another feature of an embodiment of the invention, the first wedge-shaped forming surface is coated with a partially reflective coating.

According to another feature of an embodiment of the invention, the first wedge-shaped forming surface is light transmissive, and wherein at least that part of the parallel faces in facing relationship with the first wedge-shaped forming surface is coated with a reflective coating.

According to another feature of an embodiment of the invention, the injected image introduced into the first optical waveguide is deflected from the injection direction to directions in the first set of conjugate directions by a first reflection of the first wedge-shaped shaping surface, and in the self-parallel The additional reflection from at least one of the faces is further deflected from directions in the first set of conjugate directions to directions in the second set of conjugate directions by a second reflection from the first wedge-shaped shaping surface.

According to another feature of an embodiment of the invention, there is also provided an incoupling prism adjacent or adjacent to the incoupling region of the first waveguide, the incoupling prism comprising at least one surface forming an extension of the corresponding surface of the first waveguide.

According to another feature of an embodiment of the present invention, there is also provided a light guide having two principally parallel surfaces, wherein the first waveguide is arranged such that an image outcoupled from the first waveguide is coupled into the light guide to flow in the light guide Propagated by internal reflection at the two principally parallel surfaces, the light guide also includes an outcoupling arrangement for outcoupling the image propagating within the light guide to direct the image towards the user's eye.

According to another feature of the embodiment of the present invention, a second optical waveguide is further provided, the second optical waveguide has a first pair of parallel surfaces and a second pair of parallel surfaces, and the first pair of parallel surfaces and the second pair of parallel surfaces are parallel to each other. In the direction of elongation, forming a rectangular cross-section, for guiding light by quadruple internal reflection at the first pair of parallel faces and the second pair of parallel faces, at least a part of the second optical waveguide is formed by the first wedge-shaped forming surface and the second wedge-shaped Delimited by a shaping surface, a first optical waveguide and a second optical waveguide are deployed in a stacked relationship and configured such that a projected image having a first aperture size is partially coupled into the first optical waveguide and the second optical waveguide each, and such that the second wedge-shaped shaping surface of the first optical waveguide and the second wedge-shaped shaping surface of the second optical waveguide are each used as part of an outcoupling configuration arranged to provide a The effective output aperture of the size.

According to another feature of an embodiment of the present invention, for each of the first and second optical waveguides, the first wedge-shaped shaping surface and a portion of one of the parallel faces in facing relationship with the first wedge-shaped shaping surface form The in-coupling formations, the optical device further includes a filling prism that substantially fills the wedge-shaped gap between the in-coupling formations.

According to another feature of an embodiment of the invention, the first wedge-shaped shaped surface of the second optical waveguide is coated partially reflective, thereby incoupling a part of the projected image and allowing a part of the projected image to reach the first incoupling formation.

According to another feature of an embodiment of the invention, the portion of one of the parallel faces in facing relation to the first wedge-shaped shaping surface of the first optical waveguide is coated to be partially reflective, thereby coupling in a portion of the projected image and allowing A portion of the projected image reaches the second in-coupling configuration.

According to another feature of embodiments of the invention, the first optical waveguide and the second optical waveguide are part of a stack of at least three optical waveguides.

According to another feature of an embodiment of the invention, the image outcoupled from the second optical waveguide propagates through the first optical waveguide.

According to another feature of an embodiment of the invention, the first wedge-shaped shaping surface and the second wedge-shaped shaping surface of the first optical waveguide are inclined at an oblique angle relative to the first pair of parallel faces and perpendicular to the second pair of parallel faces.

According to another feature of an embodiment of the invention, the first wedge-shaped shaping surface and the second wedge-shaped shaping surface of the first optical waveguide are inclined at an oblique angle relative to both the first pair of parallel faces and the second pair of parallel faces.

According to the teachings of the embodiments of the present invention, there is also provided an optical device, comprising: a first optical waveguide portion having at least a first pair of parallel surfaces for guiding light by internal reflection, the first optical waveguide includes an oriented a plurality of mutually parallel partially reflective surfaces non-parallel to the paired parallel planes; a wedge-like formation formed between a first wedge-shaped shaping surface and one of the parallel surfaces, the wedge-like formation being configured such that it is identical to the first Light rays corresponding to at least a portion of the injected image propagating in a first direction within the optical waveguide portion are deflected by reflection at the first wedge-shaped shaping surface to propagate in a second direction that is more consistent with the first optical waveguide than the first direction. The angle formed by the elongated directions of the part is small, and the light rays in the first direction and the light rays in the second direction are respectively deflected to the first deflection direction and the second deflection direction at the partially reflective surface to transmit from the first optical waveguide part outcoupling; a second optical waveguide having a second pair of parallel faces for guiding light by internal reflection, the second optical waveguide being arranged to receive the injected image propagating along the first deflection direction and the second deflection direction part of the second optical waveguide comprising an outcoupling wedge formation formed between the second wedge shaping surface and one of the second pair of parallel faces, the outcoupling wedge formation being deployed to pass at least the image through the wedge shaping surface A single reflection of 2 propagates in the first deflection direction and a portion of it propagates in the second deflection direction by being reflected twice from the wedge shaped surface is outcoupled.

Description of drawings

The invention is herein described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1A is a schematic front view of an optical device including a waveguide constructed and operative in accordance with an embodiment of the present invention;

FIG. 1B is a schematic front view of an optical device similar to that in FIG. 1A showing an alternative configuration for coupling in a projected image;

Figure 1C is a schematic cross-sectional view taken through the waveguide in Figure 1A, shown twice to show two different modes of image propagation;

2A is a front view of an optical device employing the waveguide in FIG. 1B and a second waveguide;

Figure 2B is a cross-sectional view taken along line A in Figure 2A;

Figure 3A is a front view of a stacked optical device employing waveguides similar to those of Figure 1A;

Figure 3B is a cross-sectional view taken along line A in Figure 3A;

Figure 4 is a front view similar to Figure 3A showing an alternative coupling configuration similar to Figure IB;

5A and 5B are schematic isometric views showing a waveguide with in-coupling prisms in accordance with the teachings of the present invention, wherein the waveguide employs oblique angles to both sets of parallel faces of the waveguide and only one set of parallel faces, respectively. The wedge-shaped forming surface;

6A to 6C are schematic top views, side views and front views, respectively, of an apparatus for realizing two-dimensional optical aperture expansion according to another aspect of the present invention;

7A and 7B are schematic side and front views, respectively, of a modified implementation of the device of FIGS. 6A-6C employing an alternative coupling geometry; and

Figures 8A-8C are schematic top, side and front views, respectively, of a device similar to the device in Figures 6A-6C implemented using two slab waveguides.

Detailed ways

The present invention is an optical device that provides aperture expansion that is particularly useful in near-eye displays.

The principles and operation of optical devices according to the present invention may be better understood with reference to the drawings and accompanying description.

Referring now to the drawings, FIGS. 1A-5B illustrate various implementations of optics providing aperture expansion particularly useful in near-eye displays, constructed and operative in accordance with a first subset of non-limiting embodiments of the present invention.

In general, the optical device comprises a first optical waveguide 30 having a direction of elongation D. As shown in FIG. The optical waveguide 30 has a first pair of parallel faces 12a, 12b and a second pair of parallel faces 14a, 14b parallel to the direction of elongation D, these parallel faces form a rectangular section for passing through the first pair of parallel faces 12a, 12b and the second pair of parallel faces 14a, 14b. The light is guided by quadruple internal reflections at parallel faces 14a, 14b. "Rectangular" in this context includes the special case of square cross-sections. As a result of this quadruple internal reflection, each ray undergoing internal reflection thus defines a set of four conjugate directions of propagation, shown for example as rays a1 , a2 , a3 and a4 in FIG. 1C .

According to one aspect of the present invention, at least a portion of the optical waveguide 30 is bounded by a first wedge-shaped forming surface 21 and a second wedge-shaped forming surface 22 that are aligned with one or more parallel planes. Adjacent regions together form corresponding wedge-shaped formations 25 and 26, respectively.

The first wedge-shaped shaping surface 21 is preferably configured such that the ray a3 corresponding to at least a part of the injected image propagates within the first optical waveguide along the first direction a3 or a4 of the first set of conjugate propagation directions a1 to a4 , a4 are deflected by reflection at the first wedge-shaped shaping surface 21 to propagate along a second direction c1 or c2 of the second set of conjugate propagation directions c1 to c4, which is elongated compared to the first direction The directions make a smaller angle. In other words, after an image has been coupled into the waveguide 30 according to a first set of conjugate directions a1 to a4, further reflection at the wedge-shaped shaping surface 21 deflects the image propagation direction into another set of conjugate directions c1 to c4 which A set of conjugate directions c1 to c4 hit the parallel surface at a shallow angle of incidence. The image propagating along the first set of conjugate directions a1 to a4 may itself be coupled in by a first reflection from the wedge-shaped shaping surface 21, as shown in Figures 1A and 1B. Thus, in the example of FIG. 1, rays of the input projected image enter the first wedge-shaped formation 25 via one of the parallel surfaces 12a, and are then reflected once from the wedge-shaped shaping surface 21 to generate a primary deflected ray corresponding to the rays a1 or a2 ( They are interchanged between each other by reflection at sides 14a and 14b). These rays are reflected at face 12a to form conjugate rays a3 and a4. For the portion of the aperture indicated by the solid arrows, the next boundary reached by rays a3 and a4 is face 12b beyond the end of the wedge-shaped forming surface. This part of the projected image is thus propagated by quadruple internal reflections as it proceeds along the waveguide, where the quadruple internal reflections are interchanged by rays a1 to a4 as shown in FIG. 1C (left). For a further portion of the aperture, rays a3 and a4 again fall on the wedge-shaped shaping surface 21, causing further deflection to generate rays c1 and/or c2, and pass through conjugate rays c1 to The quadruple internal reflection of c4 comes to propagate along the waveguide. Rays c1 to c4 make a smaller angle with the elongation direction D of the waveguide than rays a1 to a4 , but this difference is not visible in the axial view of FIG. 1C .

Incidentally, whether images are represented herein by light beams or rays, it should be noted that a beam is a sample beam of an image, and that an image is usually formed by multiple beams having slightly different angles, each corresponding to the points or pixels. The bundle shown is typically the centroid of the image, except where it is specifically referred to as the extremity of the image. Furthermore, the illumination for each pixel is not limited to a specific ray position, but is preferably a broad bundle of parallel rays that substantially "fills" the corresponding dimension of the waveguide. Thus, the sample rays shown herein are generally part of a wider continuum of rays spanning the output aperture of the image projection device.

The angle of inclination of the wedge-shaped forming surface 21 to the face 12a is preferably chosen to satisfy a number of geometrical requirements. First, for the entire field of view of the image, the wedge angle is chosen such that the primary reflected rays a1, a2 undergo internal reflection at parallel faces of the waveguide, taking into account the intended injection direction of the projected image. Furthermore, the wedge angle is chosen to be shallow enough to enable the above-described repeated reflections from the wedge-shaped shaping surface used to generate rays c1, c2 to occur while ensuring that the image fields of view in the primary and double deflection images are not in angular space. overlap. Examples of how to evaluate these conditions numerically in the case of double reflections are presented in the aforementioned '242 publication, and as will be clear to those skilled in the art, the examples can be readily adapted to the quadruple reflections in the present invention. Condition. The invention is not limited to two modes of propagation, and in particular a third propagation and its conjugate can also be used where only a relatively small angular field of view is required, wherein the third propagation and its conjugate are in the rays c1 to c4 One of is achieved after being further reflected at the wedge shaped surface.

In this case, the second wedge-shaped shaping surface 22 is parallel to the first wedge-shaped shaping surface 21, thereby forming a second wedge-shaped configuration 26 which, in a manner similar to the coupling described above, illuminates an image propagating within the waveguide. coupled out. Specifically, the second wedge-shaped forming surface 22 deflects an image propagating along at least one of the second set of conjugate directions c1 to c4 such that the image is along at least one of the first set of conjugate directions a1 to a4 propagating, and further outcoupling the image propagating along one of the first set of conjugate directions a1 to a4 so that the image leaves the optical waveguide 30 .

The configuration of Figure 1A appears in side view to be similar to the configuration described in the aforementioned '242 publication. However, the '242 publication relates to waveguides that reflect only at a pair of parallel surfaces (i.e., double reflection), and the other dimension of the waveguide (as shown in the page) is relatively large to prevent light from interfering with the waveguide. The other ends are crossed. In contrast, certain preferred embodiments of the present invention employ a rectangular waveguide approach, thereby providing guidance of image illumination in two dimensions by quadruple internal reflection, and thereby permitting the use of optical elements than can be used with a slab waveguide approach Much more compact optics.

Although wedge-shaped shaping surfaces 21 and 22 are shown here as being oblique to one pair of parallel faces 12a, 12b and perpendicular to the other pair of parallel faces 14a, 14b, the rectangular waveguide approach also allows the use of oblique angles relative to the two pairs of parallel faces. Angled wedge-shaped forming surface. One such example is shown below with reference to FIG. 5A. In general, as long as the wedge geometry is similar for the first and second wedge configurations, the outcoupling geometry still effectively "undoes" the effect of the incoupling geometry.

In the configuration of FIG. 1A , depending on the angle of injection of the projected image and the angle of the wedge itself, the wedge shaped surface 21 can in some cases achieve sufficient internal reflection without the need for a coating. In most cases, however, it is preferred to provide the wedge-shaped forming surface 21 with a reflective coating, or in some cases, as discussed further below, a partially reflective coating. The second wedge-shaped forming surface 22 is preferably provided with a reflective coating. The reflective coating (shown here in bold) can be achieved using metallic coatings or dielectric coatings as known in the art.

FIG. 1B illustrates an alternative coupling geometry, which in some implementations may be advantageous for a more compact overall product form factor. In this case, the first wedge-shaped shaping surface 21 is the light-transmitting outer surface of the optical waveguide 30 and is the surface through which the injected image is guided. At least that part of the face 12a in facing relationship with the first wedge-shaped forming surface 21 is coated with a (fully or partially) reflective coating 27 so as to reflect all or part of the injected image back to the wedge-shaped forming surface 21 where it The ray undergoes a reflection which is equivalent to the first reflection in the configuration of FIG. 1 . The rest of the reflections are similar to those described above in connection with Figure 1A.

The in-coupling configuration in FIG. 1B includes a variation that employs a larger waveguide in another dimension to accommodate the entire field of view of the image in waveguide 30 with only two reflections (i.e., otherwise similar to that in the '242 publication above). The configuration described), is considered to be advantageous in a wide range of applications.

Figure 2 shows an implementation of a near-eye display in which a waveguide 30 is used to convey an image to a second waveguide (or "lightguide") 20 having two principally parallel surfaces 24a, 24b, (propagated by light rays b1 and b2). ) The image is coupled out from the second waveguide towards the eye 47 of the observer. In the particularly preferred but non-limiting example shown here, the second waveguide employs a plurality of mutually parallel, inclined at an oblique angle, internal partially reflective surfaces 45 for outcoupling the image towards the eye. A light guide 20 having an interior partially reflective surface 45 can be readily realized using design and fabrication techniques known in the art, wherein similar elements can be obtained from companies including Lumus Ltd. (Ness Ziona) , Israel) are commercially available from a range of sources. Therefore, the structure of the light guide 20 itself will not be described in detail here.

In the device design shown here, the waveguide 30 is tilted relative to the direction of extension of the partially reflective surface 45 in the waveguide 20 in order to produce vertical propagation in the waveguide 20 . In some cases, it may be desirable to employ other offset angles between the two waveguides (such as a tilt about a "roll" axis along the elongate direction of waveguide 30) to provide an improved optical coupling configuration between the two waveguides. . In PCT Patent Application Publication No. WO 2018/065975A1 (which was published after the priority date of the present application and does not constitute prior art to the present application), particularly in FIGS. The various variant coupling options for , will not be discussed here for the sake of brevity.

This example employs the coupling geometry described above with reference to Figure IB. An in-coupling prism 11 is added to minimize chromatic aberration. An air gap or other low-index coupling material is provided between the incoupling prism 11 and the wedge-shaping surface 21 to maintain total internal reflection properties at the wedge-shaping surface 21 .

Turning now to FIGS. 3A-4 , these figures show how a stack of two or more waveguides can be used to achieve even greater aperture expansion. In these illustrations a stack of three waveguides 30a, 30b, 30c (each similar to waveguide 30 described so far) is arranged such that the projected input image is partially coupled into each waveguide. The lengths of the waveguides vary such that the outcoupling wedge formations are staggered, most preferably with generally coplanar wedge shaped surfaces 22 as shown, thereby providing coverage for the entire "width" dimension of the lightguide 20, which itself provides a second Aperture expansion in two dimensions, as shown in Figures 2A-2B above. Between the waveguides 30a, 30b and 30c are arranged air gaps or other internal reflection maintaining layers or multilayer structures in order to maintain the internal reflection properties of these waveguides. At least in the outcoupling region, the boundary between the waveguides must be transparent to light at low angles to allow outcoupling light to pass through the interface. In other areas, metallic reflective layers or other reflective layers may be used between the waveguides.

As can be seen in FIG. 3B , outcoupling from the wedge-shaped shaping surfaces 22 of the upper waveguides 30b and 30c guides the outcoupled image illumination (rays b1 and/or b2) through the underlying waveguides, where the front 14a and back 14b serve as light guides 20 Extension in the front-back direction. In the cross-sectional view of FIG. 3A , the rays b1 to b2 and c1 to c4 in the upper waveguide have been omitted for clarity of presentation, but these rays are still present.

The incoupling configuration of the device in FIG. 3B is based on partial reflection from the wedge shaped surface 21 . Specifically, the wedge-shaped shaped surfaces 21 of waveguides 30c and 30b are coated to be partially reflective such that when a projected image is input as shown, part of this image illumination is deflected and coupled into waveguide 30c and part is transmitted and received by is coupled into waveguide 30b, and a portion is transmitted through both waveguide 30c and waveguide 30b and coupled into waveguide 30a. The wedge shaped surface 21 of the waveguide 30a may be a perfect (ie, nearly 100%) reflector. In order to minimize distortion of the transmitted portion of the image illumination, the filling prism 31 is preferably deployed so that it substantially fills the wedge-shaped gap between the in-coupling formations. A filling prism 31 can be integrated as an extension of the waveguide and can be separated from the underlying waveguide by an air gap as shown. In some cases, for example, an incoupling prism 32 may be provided to benefit the incoupling geometry and minimize chromatic aberration.

Fig. 4 shows a device architecture similar to Fig. 3B but employing a coupling arrangement based on the principle of Fig. 1B. In this case, partial coupling into the plurality of waveguides is achieved by a partially reflective coating applied to a part of the face 12a, and the image is introduced from the side of the wedge shaped surface 21 . The uppermost waveguide 30c may employ a totally reflective coating on the relevant portion of the face 12a. Fill wedges 31 are again provided, but here shown spaced from wedge shaped surface 21 by an air gap to preserve the TIR properties of surface 21, providing low loss transmission of injected image illumination while capturing reflected lines. An incoupling prism 11 is provided.

While the implementations of the invention shown so far all use the first reflection from the first wedge-shaped shaping surface 21 to couple the image illumination into the waveguide (into the mode of rays a1 to a4), this is not a necessary feature, and Alternative coupling arrangements may be preferred. As an example, FIGS. 5A and 5B show an incoupling arrangement in which an incoupling prism 40 is adjacent or contiguous to the incoupling region of the first waveguide 30 so as to provide an inclined input surface 42 which The surfaces are correctly oriented to allow direct injection of an image along the image injection direction corresponding to one of the rays a1 to a4, wherein the remaining three conjugate rays are generated by internal reflection from the waveguide face. One of these conjugate rays is reflected from the wedge shaped surface 21 to generate one of the second mode rays c1 to c4, wherein the other three conjugate rays are regenerated by internal reflection within the waveguide.

The incoupling prism 40 preferably includes at least one surface, and preferably two surfaces 44 and 46, which are coplanar extensions of corresponding surfaces of the first waveguide (which may be the illustrated faces 12b and 14b). , or the coupling prism may include a wedge-shaped shaped surface 21 in some cases. These extended surfaces help to "fill" the waveguide with image illumination. In this implementation, the propagation of the first mode corresponding to rays a1 to a4 is injected directly into the waveguide (by injecting one of these images), while the second mode corresponding to rays c1 to c4 is injected through the wedge-shaped The forming surface 21 is formed by reflecting one of these images and then generating a conjugate image by internal reflection.

The implementations in FIGS. 5A and 5B are substantially similar, except that FIG. 5A shows that the wedge-shaped forming surfaces 21 and 22 are inclined at an oblique angle relative to both the first pair of parallel faces 12a, 12b and the second pair of parallel faces 14a, 14b. 5B, while Fig. 5B shows an implementation in which the wedge-shaped forming surfaces 21 and 22 are inclined at an oblique angle relative to the first pair of parallel faces 12a, 12b and perpendicular to the second pair of parallel faces 14a, 14b.

Turning now to FIGS. 6A-8C , these figures illustrate a second aspect of the invention according to which the first and second wedge-shaped forming surfaces are not parallel surfaces because the image illumination is at A wedge formation is deflected between a second wedge formation. In the case shown here, the deflection occurs at a series of partially reflective sloped inner surfaces within the first waveguide, wherein the series of partially reflective sloped inner surfaces achieves aperture expansion in the first dimension and redirects image illumination into towards the second waveguide.

Three non-limiting examples of such implementations will now be described. In each case, an optical device is shown comprising a first optical waveguide 140 having at least one pair of parallel faces for guiding light by internal reflection. The light guide portion 140 includes a series of mutually parallel partially reflective surfaces 150 oriented non-parallel to the pair of parallel planes. The optical waveguide portion 140 also includes a wedge-like formation formed between the first wedge-shaped shaping surface 125 and one of the parallel surfaces. The wedge configuration is configured to provide incoupling of image illumination to generate two distinct modes (or angular ranges) for propagating images within the waveguide, as described with respect to the wedge shaped surface 21 in the previous embodiments. In this case, the light rays corresponding to the two propagation modes of the image are not propagated directly to the outcoupling wedge but are deflected at the partially reflective surface 150 into corresponding deflection directions for outcoupling from the first optical waveguide.

The second optical waveguide portion 145 has a pair of parallel faces for guiding light by internal reflection, and is arranged to receive light propagating in directions corresponding to image propagation in the two modes deflected from the surface 150 in the injected image. part. The second optical waveguide portion 145 includes an outcoupling wedge-like configuration formed between the second wedge-shaped shaping surface 122 and one of the parallel faces. This outcoupling wedge configuration decouples both modes of image propagation in a manner completely analogous to the wedge shaped surface 22 described above. In the case of use as part of an augmented reality display, the wedge shaped surface 122 is preferably implemented with a partially reflective coating, and complementary wedge prisms (not shown) may be added to provide an undistorted view of the real world via the wedge configuration.

In the case of FIGS. 6A to 6C and FIGS. 7A to 7C , the first optical waveguide portion 140 is a rectangular waveguide in which image illumination is propagated by quadruple internal reflection, as described above with respect to waveguide 30 . In FIGS. 6A-6C , the in-coupling wedge formation is best seen in the top view of FIG. 6A , and the out-coupling wedge formation is best seen in the side view of FIG. 6B . An alternative realization of the coupling via the wedge-shaped shaped surface 125 can also be used analogously to FIG. 1B described above. Here, the orientation of the partially reflective surface 150 is most preferably inclined with respect to the top and bottom surfaces of the waveguide 140 and perpendicular to the front and rear surfaces, as shown in FIG. 8C .

The embodiment in Figures 7A and 7B is structurally and functionally similar to the embodiment in Figures 6A to 6C, but employs a different orientation of the coupling wedge, which may provide additional benefits in terms of product design compactness and ergonomics. flexibility. Taking into account the quadruple reflections that occur during propagation of the image within the waveguide, the desired orientation of the conjugate image may in some cases be selected for coupling out to the eye. In case the outcoupled image is an inverted image, this can be electronically compensated for by inverting the generated image so that the outcoupled image is correctly oriented. In general, the partially reflective surface 150 is inclined relative to the two pairs of parallel outer faces of the waveguide.

Turning finally to FIGS. 8A-8C , these figures show an embodiment similar to that of FIGS. 6A-6C , but in FIGS. Image lighting is directed between parallel faces in only one dimension. In another dimension (the up-down dimension as shown in Figures 8B and 8C), the image projected within the waveguide 140 spreads out according to its angular field of view and should not reach the end of the waveguide. Therefore, the waveguide 140 typically needs to be slightly larger in the non-guiding dimension than previous implementations. Since internal reflection between waveguide 140 and waveguide 145 is not required (or desired), these elements can optionally be unified or optically combined into a single waveguide plate without intervening any air gaps or other optical elements. In all other respects, the embodiment of Figures 8A-8C is similar in structure and operation to the embodiment of Figures 6A-6C described above.

In all of the above embodiments, the described devices are used in combination with a number of additional components to form a complete product. Thus, for example, wherever light is shown in connection with coupling into image illumination in the figures, such light is typically provided by a pico image projector or "POD", which typically includes an illumination source, such as an LCoS chip Spatial light modulators and collimating optics, which are usually integrated on the surface of the beam splitter prism block structure. Such image projectors are known per se and are commercially available, so they will not be described in detail here.

Similarly, in the case of near-eye displays, the final product is often integrated with a support structure, which may include a frame-type structure supported by the wearer's ears and nose, or may include a head-mounted structure such as a headband or helmet . All of these structures are well known and therefore need not be described herein.

It should be understood that the above description is intended to be exemplary only and that many other embodiments are possible within the scope of the invention as defined by the appended claims.

Claims (15)

1. An optical device comprising: A first optical waveguide (30) having an elongated direction, said first optical waveguide having a first pair of parallel faces (12a, 12b) and a second pair of parallel faces (14a, 14b), said first pair of parallel faces and said second pair of parallel faces parallel to said elongation direction, forming a rectangular cross-section, for guiding light by quadruple internal reflection at said first pair of parallel faces and said second pair of parallel faces, undergoing internal reflection Each ray of light thus defines a set of four conjugate directions of propagation, at least a portion of said first optical waveguide being delimited by a first wedge-shaped shaping surface (21) and a second wedge-shaped shaping surface (22), The first wedge-shaping surface is configured such that light rays corresponding to at least a portion of an injected image propagating within the first optical waveguide along a first direction of a first set of conjugate propagation directions pass through the first wedge-shaping surface. reflections at the surface are deflected to propagate along a second direction of a second set of conjugate propagation directions, said second direction making a smaller angle with said elongated direction than said first direction, And wherein said second wedge-shaped forming surface is parallel to said first wedge-shaped forming surface to deflect an image propagating in at least one of said second set of conjugate directions to be along said first set of conjugate directions propagating in at least one direction of the first set of conjugate directions and outcoupling an image propagating in one direction of the first set of conjugate directions away from the first optical waveguide, It is characterized in that, The optical device also includes a light guide (20) having two mainly parallel surfaces (24a, 24b), wherein the first light guide is arranged such that The outcoupled image is coupled into the light guide for propagation within the light guide by internal reflection at the two principally parallel surfaces, the light guide further comprising an outcoupling arrangement (45) for The image propagating within the light guide is coupled out to direct the image towards the user's eye (47). 2. The optical device of claim 1, wherein the first wedge-shaped shaping surface is an outer surface of the first optical waveguide. 3. The optical device of claim 1, wherein the first wedge-shaped forming surface is coated with a reflective coating. 4. The optical device of claim 1, wherein the first wedge-shaped forming surface is coated with a partially reflective coating. 5. The optical device according to claim 1, wherein said first wedge-shaped forming surface is light transmissive, and wherein at least a portion of said parallel planes in facing relationship with said first wedge-shaped forming surface is coated with Covered with a reflective coating. 6. The optical device of claim 1, wherein an injected image introduced into the first optical waveguide is deflected from the injection direction to the first set of conjugates by a first reflection of the first wedge-shaped shaping surface. directions and are further deflected from directions in the first set of conjugate directions by a second reflection from the first wedge-shaped shaping surface after an additional reflection from at least one of the parallel faces to the directions in the second set of conjugate directions. 7. The optical device of claim 1 , further comprising an incoupling prism adjacent or adjacent to an incoupling region of the first optical waveguide, the incoupling prism comprising a corresponding surface forming the first optical waveguide at least one surface of the extension. 8. The optical device of claim 1 , further comprising a second optical waveguide having a first pair of parallel faces and a second pair of parallel faces, the first pair of parallel faces of the second optical waveguide parallel faces and said second pair of parallel faces parallel to said elongation direction, forming a rectangular cross-section for guiding light by quadruple internal reflection at said first pair of parallel faces and said second pair of parallel faces, at least a portion of the second optical waveguide is bounded by a first wedge-shaped shaping surface and a second wedge-shaped shaping surface, The first optical waveguide and the second optical waveguide are arranged in a stacked relationship and are configured such that a projected image having a first aperture size is partially coupled into the first optical waveguide and the second optical waveguide. each of the optical waveguides, and such that the second wedge-shaped shaping surface of the first optical waveguide and the second wedge-shaped shaping surface of the second optical waveguide are each used as part of an outcoupling configuration, the coupling The output configuration is arranged to provide an effective output aperture having a size greater than the first aperture size. 9. The optical device according to claim 8 , wherein, for each of the first and second optical waveguides, one of the first wedge-shaped shaping surface and the parallel plane is Portions of the first wedge-shaped shaping surface in facing relationship form in-coupling formations, the optical device further comprising filling prisms substantially filling wedge-shaped gaps between the in-coupling formations. 10. The optical device of claim 9, wherein the first wedge-shaped shaping surface of the second optical waveguide is coated to be partially reflective, thereby coupling in a portion of the projected image and allowing the projected image to be partially reflective. A portion of the image reaches the first coupling-in configuration. 11. The optical device of claim 9, wherein the portion of one of the parallel faces in facing relationship with the first wedge-shaped shaping surface of the first optical waveguide is coated to be partially reflective , thereby incoupling and allowing a portion of the projected image to reach the second incoupling configuration. 12. The optical device of claim 8, wherein the first optical waveguide and the second optical waveguide are part of a stack of at least three optical waveguides. 13. The optical device of claim 8, wherein the image out-coupled from the second optical waveguide propagates through the first optical waveguide. 14. The optical device of claim 1 , wherein the first and second wedge-shaped forming surfaces of the first optical waveguide are inclined relative to the first pair of parallel planes at an oblique angle and perpendicular to the second pair of parallel planes. 15. The optical device of claim 1 , wherein the first wedge-shaped shaping surface and the second wedge-shaped shaping surface of the first optical waveguide are at an oblique angle relative to the first pair of parallel planes and the first pair of parallel planes. Both of the second pair of parallel planes are inclined.

Images